Surprises in survey of exercise and the pill

By KATHERINE HOBY

Young women who exercise and take the contraceptive pill may have an increased risk of getting osteoporosis, says a visiting US calcium expert.

Professor Connie Weaver, head of foods and nutrition at Purdue University in Indiana, says a two-year study on bone density in young women produced alarming results.

The study of 180 women between the ages of 18 and 30 originally aimed to test the effects of exercise on young women's bone density.

"We thought, if anything, that young healthy women who were exercising would increase bone mass," said Professor Weaver. "We were in for some big shocks."

The study recruited women who were previously sedentary and chose half the group at random to exercise.

Results showed that the control exercise group, which was also taking the oral contraceptive pill, lost bone mass.

"It was quite a staggering finding because it negated a lot of commonly held assumptions," said Professor Weaver.

It had been thought that young women continued achieving peak stable bone mass until menopause. The earliest age for people losing bone density was thought to be 50 to 55, she said.



"I expected the control group would still be gaining mass right up through their 20s. Instead, they lost 1.5 per cent over the two years."

To further prove the point, the non-exercisers gained a little over 1 per cent mass.

Professor Weaver said the only women in the control group who were unaffected by the exercise were those taking a daily calcium supplement.

"Not only did the exercisers lose bone mass, but they lost it in the two bones where you most want to sustain mass - the hip and the spine," she said.

"We want to more rigorously test this, of course, but the numbers are significant enough to show me that there's a risk of osteoporosis occurring much, much earlier than we thought."

Young women had been "ignored too long" by osteoporosis researchers, said Professor Weaver.

"They have been told one thing and end up waiting too long to make the lifestyle changes needed.

"I'm not going to tell them to stop taking the pill or stop exercising but I would advise, until we know for sure, to get your calcium intake up.

"If this theory bears up, calcium is the only way to prevent bone mass loss."

Osteoporosis New Zealand executive manager Julia Gallagher said that although Professor Weaver's findings were preliminary, they were interesting.

"She is one of the best researchers in the area of bone density in young women," said Julia Gallagher.

"We would very much like to see any further findings."

nzherald.co.nz/health